This proposal is designed to study, by employing in vitro autologous leukemia system and syngeneic guinea pig line 10-tumor model, the possibility of developing immunotherapy for cancer. The objectives are to: 1. Generate cytotoxic lymphocytes in vitro against autologous leukemia cells. a. Assess the cell mediated cytotoxicity in 3 hour 51Cr release assay before and after in vitro stimulation of lymphocytes. b. Stimulate remission lymphocytes with autologous and/or allogeneic leukemia cells. c. Stimulate remission lymphocytes with leukemia cells and/or soluble bacterial extracts. 2. Determine the specificity of effector lymphocytes before and following in vitro sensitization. a. Determine specificity of leukemia stimulated lymphocytes. b. Determine specificity of leukemia plus bacterial or bacterial stimulated lymphocytes. 3. Study the nature of cytotoxic lymphocytes or precursors of cytotoxic lymphocytes. 4. Generate line-10 tumor specific lymphocytes in vitro and study immunoprevention and immunotherapy of syngeneic strain-2 guinea pig line-10 hepatocarcinoma by these effector lymphocytes. a. Produce cytotoxic lymphocytes by sensitization of lymphocytes with line-10 tumor cells, tumor cell fractions and/or bacterial extracts and determine the feasibility of producing large numbers of sensitized lymphocytes. b. Assess the biologic importance of in vitro sensitized lymphocytes. Syngeneic line-10 tumor specific sensitized lymphocytes will be used to determine the effects on 1) tumor implantation, 2) the growth of previously established and growing tumors, and 3) the behavior of regressing tumors.